JP2002027755A - Ac/dc converter and motor drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC/DC converter and a motor driving system which can eliminate not only noise generated between buses but also noise generated between the bus and ground. SOLUTION: In a DC line from which a waveform rectified by a rectifier D is outputted, noise eliminating capacitors C3 and C4 are connected between a bus P and the ground G and between a bus N and the ground G, respectively, thereby eliminating noise between the buses P, N and the ground G (frame ground of a fiber machine). A resistor R2 and a resistor R3 as current suppression elements are connected in series with the capacitor C3 and the capacitor C4, thereby suppressing rush currents 1a and 1b which flow when surge in a common mode is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC-DC converter having a rectifying unit for rectifying and smoothing an AC input and a smoothing element, and a motor drive system having the same.

[0002]

2. Description of the Related Art An AC-DC converter for converting AC power from an AC power supply into a DC output is provided with a rectifying section for rectifying the AC power, and for smoothing the output rectified by the rectifying section. And a rectifying unit,
An example in which a plurality of diodes are configured in a bridge type is used, and a smoothing capacitor is used as the smoothing element. Further, in the AC-DC converter, in order to absorb and remove high-frequency noise generated between buses of a circuit (referred to as a DC line) that outputs a rectified waveform, the AC-DC converter is connected in parallel with a smoothing capacitor between the buses. A noise removal capacitor is connected.

[0003]

The above-mentioned noise removing capacitor removes noise generated between the buses of the circuit in the AC-DC converter.
It is not effective for removing noise generated between
In particular, in a single-spindle-drive type textile machine in which a large number of units are arranged in parallel and each unit includes a drive motor and an inverter, the inverter is connected to one AC-DC converter through a common bus. In the case of the motor drive system described above, since the power supply lines are routed and connected from the common AC-DC converter to all the inverters of each unit, noise is generated between the above-described bus and ground (ground). However, there is a problem that this is likely to occur.

For example, there is a case where an IC for detecting that the voltage between the buses has increased due to generation of regenerative power and switching a regenerative switch is provided in the AC-DC converter. In this IC, the voltage between the buses is driven by a predetermined voltage divided by a resistor serving as a current suppressing element. In this case, noise generated between the bus and ground (ground) may cause the IC to malfunction or be damaged if the noise is applied to the divided voltage line.
Malfunction or breakage of C has an effect such as breakage of the inverter and other elements.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an AC-DC converter capable of removing not only noise generated between buses but also noise generated between the buses and ground (ground). And a motor drive system.

[0006]

According to an aspect of the present invention, there is provided an AC-DC converter including a rectifying unit for rectifying and smoothing an AC input and a smoothing element. Each bus from which the rectified waveform is output is grounded via a noise removing element. According to the present invention, since each bus outputting the rectified waveform is grounded via the noise removing element, it is not effective in the noise removing capacitor for removing noise generated between the buses of the circuit in the AC-DC converter. , Noise generated between the bus and the ground (ground) can be removed.

According to a second aspect of the present invention, a current suppressing element is provided between the DC output portion after the rectification and smoothing and the ground. In the present invention, by providing the current suppressing element between the DC output portion after the rectification and smoothing and the ground, the bus is grounded via the noise removing element, so that the common mode from the outside due to lightning or the like is provided. It is possible to suppress a large current generated in a circuit in the AC-DC converter at the time of applying a surge.

According to a third aspect of the present invention, the current suppressing element is connected in series with the noise removing element. According to the present invention, the current suppressing element is connected in series with the noise removing element, so that the current suppressing element is easily generated when the current suppressing element is provided on the bus. In order to prevent burn-in due to the supplied current always flowing through the bus (current suppressing element), it is possible to avoid the necessity of providing a large capacity (power).

According to a fourth aspect of the present invention, there is provided a motor drive system in which a plurality of motors are arranged side by side and a DC-AC converter is provided for each motor. -It is characterized in that a DC output from the DC converter is supplied to a plurality of DC-AC converters through a common power supply line. According to the present invention, in a motor drive system including a plurality of motors arranged in parallel and a DC-AC converter for each motor, a DC output by the AC-DC converter according to any one of claims 1 to 3. Is supplied to a plurality of DC-AC converters through a common power supply line, so that the DC-AC converter (inverter) is connected to the AC-DC converter via a common bus. In this case, noise between the bus and ground (ground) can be removed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the embodiments unless it departs from the gist of the present invention.

FIG. 1 is a circuit diagram of an AC-DC converter 1 according to an embodiment of the present invention, and FIG. 2 is a single spindle driving type fiber provided with a driving motor M and an inverter INV for each unit U. FIG. 2 is a circuit block diagram showing a motor drive system using the AC-DC converter 1 of FIG. 1 for a machine.

As shown in FIG. 2, in the embodiment of the present invention, the textile machine is a single-spindle-drive textile machine in which a number of units U are arranged in parallel, and each unit U is provided with a drive motor M and an inverter INV. is there. In the drive system of the motor M in this textile machine, the inverter INV is connected to a common AC-DC converter 1 (hereinafter referred to as an AC-DC converter 1) via common buses P and N. A power supply line is routed from the AC-DC converter 1 to all the inverters INV of the units U.

As shown in FIG. 1, the AC-DC converter 1 shown in FIG.
Connected to terminals AC, R, S and T
A breaker (not shown) is attached between the phase AC power supply AC and the terminals R, S, and T. The AC-DC converter 1 includes a rectifier D for rectifying an AC input and a smoothing capacitor C1. In an AC line portion between the rectifier and a power supply, a surge absorber 2 and a terminal R are provided between a terminal R and a ground G. Varistors 3, 4, and 5 are connected between -S, ST and RT.

In the DC line from which the waveform rectified by the rectifier D is output, a resistor R1 is connected on the bus P in parallel with the switch contact 6. Furthermore, the bus P-
A smoothing capacitor C1, a capacitor C2 as a noise removing element, and a varistor 7 are connected in parallel between N.
Apart from the noise eliminating capacitor C2, a noise eliminating capacitor C is provided between the bus P and the ground G and between the bus N and the ground G.
3, C4 are connected. Further, a noise removing capacitor C3, a resistor R2 as a current suppressing element, and a noise removing capacitor C4 and a resistor R3 are connected in series.

Inside the AC-DC converter 1, an IC (not shown) for detecting that the voltage between the bus P and the bus N has risen due to the generation of regenerative power from the motor M and switching the regenerative switch is provided. Is provided. This IC is
It is driven by a predetermined voltage obtained by dividing the voltage between the bus P and the bus N by a resistor which is a current suppressing element.

In the drive system for the motor M of the textile machine shown in FIG. 2, the AC power supplied from the three-phase AC power supply AC is once converted into a DC output by the AC-DC converter 1, and the DC output is converted to the buses P, The power is supplied to the inverter INV of each unit U via N.

Next, in the circuit of the AC-DC converter 1 shown in FIG. 2, the rectifier D is composed of, for example, a plurality of diodes connected in a bridge type.

Here, in the AC line between the three-phase AC power supply side and the rectifying unit D, the surge absorber 2 between the terminal R and the ground G causes the potential between the terminal R and the ground G to be a predetermined voltage. When it reaches, the resistance value drops sharply.
Also, the varistors 3, 4, and 5 between the terminals RS, ST and RT (normal mode) have their resistance values non-linearly decrease as the potential between the terminals rises. It has become.

Switch contact 6 on bus P of DC line
Is in an open state immediately after the start of power supply from the three-phase AC power supply AC, and a current flows through the current suppressing element (resistance) R1 connected in parallel with the switch contact 6. This is to suppress the instantaneous inrush current (large current) value generated immediately after the power supply of the AC-DC converter 1 is started by the resistor R1, and to prevent destruction of circuit elements due to the inrush current.

Further, the noise elimination capacitor C2 between the buses PN is adapted to remove high-frequency noise generated between the buses PN. The varistor 7 is similar to the varistors 3 to 5 described above. When a surge occurs due to lightning or the like between the buses PN, the buses PN are short-circuited to prevent each circuit element in the DC line from being damaged by overvoltage.

The resistors R2 and R3 are connected in series with the noise removing capacitors C3 and C4, so that the resistors R2 and R3 are provided on the buses P and N, respectively. Power supply A when DC converter 1 operates
The current supplied from C is always the buses P, N (resistors R2, R
3) It is possible to prevent burn-in of the resistors R2 and R3 due to the flow in 3).

The three-phase AC output from the three-phase AC power supply AC is full-wave rectified by the rectifier D of the AC-DC converter 1. Here, in the DC line immediately after the start of the power supply from the three-phase AC power supply AC, the switch contact 6 on the bus P
Is opened for a predetermined time immediately after switching, whereby a current flows through the resistor R1 and the AC-DC
The rush current immediately after switching of the converter 1 is represented by a resistor R
After the suppression at step 1, the switch contact 6 is short-circuited.

The full-wave rectified waveform is smoothed by the smoothing capacitor C1 so that ripple is reduced to provide a DC output. This DC output is input to the inverter INV of each unit U of the textile machine connected to the buses P and N, as shown in FIG. Here, the inverter INV controls the frequency of the output supplied to the motor M, whereby the rotation speed control (stop, forward rotation, reverse rotation control, etc.) of the motor M according to the operating condition of each unit U is performed. ) Is performed.

The noise between the buses P and N in FIG. 1 and the ground G (frame ground of the textile machine) is removed by the capacitors C3 and C4. This can prevent the IC for regenerative power detection from malfunctioning or being damaged, and prevent the inverter and other elements from being damaged due to malfunction or damage of the IC.

When a surge due to an external factor such as lightning is applied in the normal mode to the AC line between the three-phase AC power supply of the AC-DC converter 1 and the rectifier D shown in FIG. 3, 4, and 5 are terminals RS
The terminals are short-circuited with the rise in the potential between the terminals, between the terminals ST and between the terminals RT.

In the AC-DC converter 1, when a surge due to an external factor such as lightning is applied between the terminal R and the ground G (common mode), the AC between the three-phase AC power supply and the rectifier D is changed. In the line, the resistance value of the surge absorber 2 between the terminal R and the ground G sharply drops, and the terminal S and the ground G are short-circuited. In addition, the rectifier D is prevented from being damaged by overvoltage.

Further, when a surge due to an external factor such as lightning is applied to the AC-DC converter 1 in the common mode, the DC line is connected between the bus P and the ground G and between the bus N and the ground G.
The connection between them causes a rush current Ia or Ib as shown in FIG. 1 to flow. However,
Since resistors R2 and R3, which are current suppressing elements, are connected in series with the noise removing capacitors C3 and C4, and the resistors R2 and R3 are connected between the bus P and the ground G and between the bus N and the ground G, respectively. The rush currents Ia and Ib are suppressed.
This prevents circuit elements such as the diode of the rectifier D from being destroyed by the rush current.

As described above, in the DC line from which the rectified waveform by the rectifying unit D is output, between the bus P and the ground G, and
Each noise elimination capacitor C3, C
4, the buses P and N and the ground G (textile machine), which are likely to be generated when the power supply lines are routed and connected from the common AC-DC converter 1 to all the inverters INV of the respective units U. Noise between the image and the frame ground) can be removed.

[0029]

The present invention is configured as described above.
The following effects are obtained.

According to the first aspect of the present invention, an AC-DC converter including a rectifying unit for rectifying and smoothing an AC input and a smoothing element.
In the DC converter, since each bus outputting a rectified waveform is grounded via a noise removing element, noise generated between the bus and ground (ground) can be removed. Therefore, malfunction or breakage of the regenerative power detection IC can be prevented, and damage to the inverter and other elements due to malfunction or breakage of this IC can be prevented.

According to the second aspect of the present invention, since the current suppressing element is provided between the DC output portion after the rectification and smoothing and the ground, the bus is grounded via the noise removing element. When a surge in a common mode is applied from the outside due to lightning or the like, a large current generated in a circuit in the AC-DC converter can be suppressed. Therefore, it is possible to prevent the circuit element of the AC-DC converter from being destroyed by the large current.

According to the third aspect of the present invention, since the current suppressing element is connected in series with the noise removing element, a current suppressing element having a small capacity (power) can be used.

According to the fourth aspect of the present invention, there is provided a motor drive system in which a plurality of motors are arranged in parallel and a DC-AC converter is provided for each motor. By supplying the DC output from the AC-DC converter to a plurality of DC-AC converters via a common power supply line, noise between the bus and ground (ground) can be removed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an AC-DC converter according to an embodiment of the present invention.

FIG. 2 is a circuit block diagram showing a motor drive system using the AC-DC converter of FIG. 1 in a single-spindle type textile machine provided with a drive motor and an inverter for each unit.

[Explanation of symbols]

 1 AC-DC Converter C1 Smoothing Capacitor C2, C3, C4 Noise Removal Capacitor D Rectifier INV Inverter M Motor R1, R2, R3 Resistance U Unit

Claims (4)

[Claims] An AC-DC converter having a rectifying section for rectifying and smoothing an AC input and a smoothing element, wherein each bus outputting a rectified waveform is grounded via a noise removing element. An AC-DC converter characterized by the above-mentioned. 2. The AC-DC converter according to claim 1, wherein a current suppressing element is provided between the rectified and smoothed DC output portion and the ground. 3. The AC-DC converter according to claim 2, wherein said current suppressing element is connected in series with said noise removing element. 4. A motor drive system in which a plurality of motors are arranged side by side and a DC-AC converter is provided for each motor.
A motor drive system, wherein a DC output from the AC-DC converter according to any one of claims 1 to 3 is supplied to a plurality of DC-AC converters via a common power supply line.